Zeolites, both natural and synthetic, have been used in a variety of catalytic and adsorptive operations. Most zeolitic materials are porous ordered aluminosilicates having a definite (although often undetermined) crystal structure. The structure may have a number of small cavities interconnected by a number of still smaller channels. These cavities and channels are uniform in size within a certain zeolitic material. The above-mentioned catalytic and adsorptive processes make use of these cavities and channels since by proper choice of zeolite, the zeolite channels will reject some molecules because of their size and accept others.
These zeolites typically are described as a rigid three-dimensional framework of silica and alumina wherein the silica and alumina tetrahedra are linked through common oxygen atoms. The charge balance of the zeolite may be satisfied by inclusion of a proton, metal, or ammonium cation. The catalytic and adsorptive properties of the zeolite may be varied by changing the ions within the zeolite. Conventional ion exchange techniques may be used to change those cations.
Similarly, there are a large number of both natural and synthetic zeolitic structures. The wide breadth of such numbers may be understood by considering the work Atlas of Zeolite Structures by W. M. Meier and D. H. Olson (Butterworths Press (1988)). Many natural zeolites are quite difficult to synthesize using the present state of the art, several of which have not yet been made synthetically. See, Robson, Chem. Tech. (1978), p. 180.
There are a large number of methods for producing zeolitic materials. May of these synthetic methods utilize mixtures of alumina, silica, a base and water, and control the typical zeolite produced by varying the reactant concentrations, temperature and pressure of reaction, and time of reaction. Other methods of controlling the type of zeolite produced include the use of zeolitic seeds as nucleation centers, combinations of solvents, or organic ammonium salts as "templates" in the reaction mixture.
The use of quaternary ammonium salts as templates or reaction modifiers in the preparation of synthetic crystalline aluminosilicates (zeolites), first discovered by R. M. Barrer in 1961, has led to preparation of a number of zeolites which are not found in nature. For example, U.S. Pat. No. 4,086,859 discloses preparation of a crystalline zeolite thought to have the ferrierite-like structure (ZSM-21) using a hydroxyethyl-trimethyl sodium aluminosilicate gel. A review provided by Barrer in Zeolites, Vol. I (1981), p. 136, shows the zeolite types which are obtained using various ammonium organic bases as cation. In addition, Breck, Zeolite Molecular Sieves, John Wiley (New York, 1974), pp. 348-378, provides a basic review of zeolites obtained using such ammonium cations in the synthesis thereof.
The zeolite of this invention is produced using potassium and/or rubidium and/or barium and organic ammonium ion (tetraethylammonium) and sodium as essential components in the synthesis mixture. It has the general chemical composition: EQU aR20:bNa.sub.2 O:c(K,Rb,Ba.sub.0.5).sub.2 O:(Al).sub.2 O.sub.3: 3-10 SiO.sub.2
where a+b+c=0.9 to 1.2 and R may be tetraethyl ammonium (TEA) or methyl triethyl ammonium (ME.sub.3) ions. However, unlike any other synthetic zeolites previously disclosed (See, H. E. Robson, supra) the inventive zeolite has a structure similar to the mineral paulingite. Paulingite is a very rare mineral which is classified as a member of the faujasite group. The mineral was first reported by Kamb and Oke, Amer. Mineral. 45, p. 79, 1960. The mineral's structure has been reported to be complex and its composition to be: EQU (K.sub.2 Na.sub.2 CaBa).sub.76: (Al.sub.152 Si.sub.525 O.sub.1354):700 H.sub.2 O
See, Gordon et al, Science 154. p. 1004, 1966. A recent review of paulingite can be found in "Natural Zeolites", by Gottardi & Galli ((1985), Springer-Velag, Berlin).
The synthetic zeolite (ECR-18), is previously reported only in a di-cation form (U.S. Pat. No. 4661332). This process for producing ECR-18 in a necessary tri cationic form has not been previously disclosed. The absence of one of these cations yields non-ECR-18 zeolites such as faujasite, chabazite and L.